drm/amdgpu: free up the first paging queue v2

We need the first paging queue to handle page faults.

v2: handle any number of SDMA instances gracefully
Signed-off-by: NChristian König <christian.koenig@amd.com>
Reviewed-by: NFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c

@@ -2265,8 +2265,8 @@ static const struct amdgpu_buffer_funcs sdma_v4_0_buffer_funcs = {
 static void sdma_v4_0_set_buffer_funcs(struct amdgpu_device *adev)
 {
 	adev->mman.buffer_funcs = &sdma_v4_0_buffer_funcs;
-	if (adev->sdma.has_page_queue)
-		adev->mman.buffer_funcs_ring = &adev->sdma.instance[0].page;
+	if (adev->sdma.has_page_queue && adev->sdma.num_instances > 1)
+		adev->mman.buffer_funcs_ring = &adev->sdma.instance[1].page;
 	else
 		adev->mman.buffer_funcs_ring = &adev->sdma.instance[0].ring;
 }
@@ -2285,15 +2285,21 @@ static void sdma_v4_0_set_vm_pte_funcs(struct amdgpu_device *adev)
 	unsigned i;
 
 	adev->vm_manager.vm_pte_funcs = &sdma_v4_0_vm_pte_funcs;
-	for (i = 0; i < adev->sdma.num_instances; i++) {
-		if (adev->sdma.has_page_queue)
+	if (adev->sdma.has_page_queue && adev->sdma.num_instances > 1) {
+		for (i = 1; i < adev->sdma.num_instances; i++) {
 			sched = &adev->sdma.instance[i].page.sched;
-		else
+			adev->vm_manager.vm_pte_rqs[i - 1] =
+				&sched->sched_rq[DRM_SCHED_PRIORITY_KERNEL];
+		}
+		adev->vm_manager.vm_pte_num_rqs = adev->sdma.num_instances - 1;
+	} else {
+		for (i = 0; i < adev->sdma.num_instances; i++) {
 			sched = &adev->sdma.instance[i].ring.sched;
-		adev->vm_manager.vm_pte_rqs[i] =
-			&sched->sched_rq[DRM_SCHED_PRIORITY_KERNEL];
+			adev->vm_manager.vm_pte_rqs[i] =
+				&sched->sched_rq[DRM_SCHED_PRIORITY_KERNEL];
+		}
+		adev->vm_manager.vm_pte_num_rqs = adev->sdma.num_instances;
 	}
-	adev->vm_manager.vm_pte_num_rqs = adev->sdma.num_instances;
 }
 
 const struct amdgpu_ip_block_version sdma_v4_0_ip_block = {